Gmail features labels and filters to better organize your contacts into groups and to more quickly and efficiently organize your e-mails into a variety of categories. Most e-mail software offer folders for this purpose. The only problem with a folders is that it can only be sent to one folder. Then when you need to access that one e-mail it can take a little longer to find. With it being stored under a variety of labels you can quickly search the labels that pertain to the e-mail in question and find it more rapidly in this process.
Labels aren't the only amazing feature Gmail has to offer. Sticking with the idea of Contacts, Gmail offers a more detailed option to your contact list so you can include details for projects, events, even birthdays. So when you are communicating with that person you have easy access to that information. Contacts that are available are posted in the left side column so you can easy invite them to chat in "hangouts".
Gmail has other features that include: tasks, labs, and text, voice and video chat. With tasks you can manage your to-do list directly from e-mails. Labs can be found in the settings tab located in the top right hand corner. Labs include but are not limited to such features as "canned responses," multiple in-boxes, smart labels, add any gadget using URL, adding app search, and many more. These labs are called labs because that is precisely what they are, they are experiments that may not always work.
Text, voice and video chat offers opportunities to personalize your communication with both students and parents. Sometimes it's hard to interpret the mood of a message in text. Being able to hear and/or see the person you are talking to makes it possible to do so.
I hope you've gained some insight into the awesomeness of Gmail and consider using it to lighten your load and add another form of communication with your student's and their parents.